Incinerator for refuse material



arch 21, 1967 J. H. JACOBS' INCINERATOR FOR REFUSE MATERIAL Filed March 5, 1964 AIR INVENTOR JOHN H. JACOBS ATTORNEY:-

United States Patent 3,310,009 INCINERATOR FGR REFUSE MATERIAL John H. Jacobs, 5908 Sherwood, Oakland, Calif. 94611 Filed Niar. 5, 1964, Ser. No. 349,598 4 Claims. (Cl. 110-8) This invention relates generally to apparatus for burning combustible materials and it more particularly relates to an apparatus for unattended complete burning of material without emission of smog producing contaminants and other air pollutants.

One object of this invention is to provide a method for automatically and completely burning combustible materials and emitting from the combustion zone a flue gas having a minimum of air contaminants, odors, smoke and other pollutants.

Another object of this invention is to provide an automatic incinerator and combustion control apparatus for completely burning a variety of combustibles without emission of smog producing contaminants or other air pollutants.

A further object of this invention is to provide means for drawing combustion air into staged combustion zones of a furnace and for withdrawing the combustion products from the staged zones in a manner which provides complete volatilization of combustibles in a first zone and complete combustion of the volatilized combustibles in a second high temperature zone.

Another object of this invention is to provide an apparatus for controlling gas flow through a closed loop combustion system to preclude contaminant emission even with varying combustion loads.

Other objects and advantages of this invention will become apparent from a consideration of the following description of the method of this invention and of an incinerator employing the method as illustrated in the accompanying drawings wherein FIG. 1 is a schematic diagram illustrative of the method of this invention;

FIG. 2 is a cross-sectional elevational view of an incinerator employing the method of this invention; and

FIG. 3 is a horizontal sectional view of the incinerator taken along line 33 of FIG. 2.

The operation of this invention comprises continuously or intermittently feeding combustible materials into a primary relatively low temperature combustion zone; drawing combustion air into the primary combustion zone in an amount less than that required for complete combustion of the combustible material; and then partially burning but completely volatilizing the combustible material in the zone. The gaseous combustion products of the primary combustion zone are then drawn into a secondary high-temperature combustion zone. To this zone is supplied sufficient combustion air to completely burn the unburned volatilized combustible. Additional heat is supplied to the inflowing gases in the secondary combustion zone and gas flow from the zone is restricted so that burning within the secondary combustion zone occurs at a high temperature to insure complete combustion of the volatilized material. The products of the complete combustion then are drawn into a cooling zone where they are combined with a controlled amount of cooling air. The volume of cooling air also funtcions to balance the gas flow through the system. The cooled gases pass through a water spray, which removes fly ash and further cools the flue gases, and then are emitted to the atmosphere.

In the described embodiment of operation of this invention, the combustible material either continuously or intermittently is admitted to primary combustion chamber 11. Primary combustion air in the amount of 3,310,009 Patented Mar. 21, 1967 65-75% of the theoretical amount required for complete burning is drawn into the chamber through a sized opening 12 by induced draft fan 13. The fan draws gases into and through the entire system. All the combustible material is volatilized or burned completely in the primary combustion zone. The only thing which remains after primary combustion in this chamber is ash which is periodically removed. The products of the primary combustion pass through a sized orifice 14 into a secondary high temperature combustion chamber 15. Secondary air in the amount of 3S25% of the theoretical amount is drawn into chamber 15 through sized openings 16 by the induced draft fan 13 to complete combustion. Flow out of the secondary combustion chamber is re stricted by orifice 17 and a baflle arrangement and supplemental heat is added 'to maintain a high combustion temperature within the chamber 15.

The products of the complete combustion then are drawn into a cooling chamber 18 by induced draft fan 13 where they are mixed with cooling air entering dampered opening 19. The cooled flue gases and air then pass into spray cooling chamber 29 where a water spray as from nozzle 21 further cools the flue gases and removes fly ash from the gas stream. Approximately excess air enters opening 19 to provide a large share of the fan load and to thereby balance the system. The cooled flue gas then is drawn through the induced draft fan blading and exhausted through flue 22 to the atmosphere.

In this manner a variety of combustible materials and industrial wastes are completely and automatically oxidized and the emitted flue gases contain no smog producing air contaminants or pollutants even for variable combustion loadings and prolonged exposure to overfire air through an open charging door. Furthermore, since an induced draft system is employed all combustion takes place at less than atmospheric pressure. This reduces the hazard of incidental leakage of combustion materials and combustion products prior to their complete burning. The method may also be completely automated.

FIG. 2 illustrates one embodiment of an incinerator employing the apparatus of this invention. The incinerator referred to generally as 25 comprises a rigid, usually steel, casing 26 which defines the exterior boundaries of the primary combustion zone 11, the secondary combustion zone 15, cooling zone 18, spray cooling zone 20, and flue 22. The illustrated incinerator is lined with high temperature castable refractory material in chambers 11, 15, and 18. Equivalent materials also may be employed. Cooling chamber 20 and flue 22 are low temperature regions and generally require no refractory lining.

Combustible material 10 is introduced to the primary combustion chamber 11 through charging door 27. Introduction may be intermittent, as shown, or continuous. The material is placed upon supporting grates 28, 29, which in turn are supported by a grill 30 overlying the ash pit 31.

The combustible material within the primary combustion chamber 11 is ignited by ignition burner 32. This ignition burner comprises, for example, an atmospheric gas burner with continuous spark ignition. The primary combustion chamber is provided with a sized air opening 12 for admission of primary combustion air into the chamber 11. An induced draft fan, referred to generally as 13, and comprising blading 33 in the exhaust flue 22 and a motor driven belt drive 34 draws air into the primary combustion chamber through the opening 12. The opening is sized with respect to the charge of combustible to provide less than the full amount of the combustion air necessary for complete burning of the combustible material. A satisfactory size opening allows admission of about 6575% of the theoretical air required for complete combustion.

The combustion products are drawn by the induced draft fan out of the primary combustion chamber through orifice 14 which opens upwardly into the secondary combustion chamber 15. Although the secondary combustion chamber may be remote from the primary combustion chamber, the described embodiment provides them in close adjacency. The fioor 35 of the secondary combustion chamber also defines the top of the primary combustion chamber. It and the vertical furnace side wall 36 define rectangular shaped orifice 14. Vertical bafiles 3'7, 38 are provided within the secondary combustion chamber to define a restricted path for gas flow through orifice 39.

Secondary combustion chamber gas burners 4t} fire into the secondary combustion chamber adjacent to orifice 1d and upstream of orifice 39. These two burners also may be atmospheric type gas burners. Each is surrounded by an air opening 16 through which the induced draft fan draws the secondary air required for complete burning. Whereas the ignition burner 32 is used principally to ignite the combustibles in the primary combustion chamber and may be closed down after combustion is started, the secondary burners 40 operate continuously on a closed control loop based on flue gas temperature to supply heat necessary for complete combustion within the secondary combustion chamber. Bafiles 37, 38 help hold this temperature by restricting gas flow through orifice 39 and out of the chamber.

A further restriction is provided by secondary combustion chamber outlet orifice 17 defined by the top 41 of the secondary combustion chamber and the refractory side wall 42 of the furnace. Through this restricting orifice the induced draft fan draws the final products of combustion into the cooling chamber 18. In this cooling chamber the gas flow is bathed by bafile means 43 and the combustion products are thereby thoroughly mixed with excess cooling air entering through opening 19 provided with a pivotable weighted damper 44-. About 100% excess air is drawn by fan 13 into the system at this point to fully load the fan and provide system balance.

The cooling chamber 18 communicates with spray cooling chamber 20 by means of aperture 45. The spray nozzle 21 within the spray chamber 20 sprays water or equivalent cooling media into the flue gas stream as it is drawn through the chamber by the induced draft fan 13. Cooling air also may be admitted into the spray cooling chamber through opening 46 to further cool the gases if desired. Ambient temperature cooling Water both cools the hot gases and removes suspended fly ash. Water which is not evaporated or entrained passes to a sump 47 and is discharged through drain opening 46. The cool flue gas then passes through the induced draft fan blading 33 and is discharged out flue 22.

Throughout the entire system the quantity of combustion air is metered to provide incomplete combustion, but complete volatilization of the combustible material, within the primary combustion chamber and then complete combustion in the secondary combustion chamber. A single induced draft fan 13 operates at a constant speed to maintain the entire system at less than atmospheric pressure and to draw a constant gas volume through the system. The volume of air admitted to the various combustion and cooling chambers is controlled by sizing the air inlets. Orifices between chambers control internal gas flow. The size of the air inlets 12 and 16 and the orifices 14, 39 and 17 are critical to obtain the combustion and flow characteristics of this system. The area of opening 12 into the primary combustion chamber (including an assumed door and ash pit leakage) is designed to be equal to that of the orifice 14. The orifice 38 between bafiles 37, 33 is established at 110-140% f the total of the area of the secondary combustion air openings 16 around the secondary combustion burners plus the area of orifice 14. This relationship throttles the gas flow through the system to hold a high combustion temperature within the secondary combustion chamber. The baffles thoroughly mix the burning gases to insure complete combustion. To confine the burning within the secondary combustion chamber, orifice 17 is sized at iii-% of the total area of the orifice 39 between baffles. The path of the gases through. the rest of the system has a gradually expanding cross section to reduce pressure loss through the system.

One specific embodiment of this invention provides 400 lbs. per hour of rated incineration capacity. An induced draft fan capable of handling 2400 c.f.m. of exhaust gases is provided to draw the combustion products through and air into the incinerator. The area of the opening 12 to the primary combustion chamber 11 (including an assumed value for leakage through the charging door and ash pit) is established for this capacity at about 60 sq. in. or some 6575% of the theoretical combustion air required. Therefore, the orifice 14- is sized at 60 sq. in. For this rated capacity the area of openings 16 supplying the balance of the combustion air are about 12 sq. in. They admit 35-25% or the balance of the theoretical air requirements. The orifice 39 between baffles 37, 38 is established at 96 sq. in. and orifice 17 at 120 sq. in.

To operate the described incinerator the secondary burners 40 are generally turned on for some 10 minutes to reheat the secondary combustion chamber. Cornbustible material is fed to combustion chamber 11. The ignition burner 32 is ignited and combustion commences. The ignition burner then may be shut down. In the event wet or damp refuse is supplied to the primary combustion chamber it may be desirable to continue operation of the ignition burner to dry out the material. The supply of gas to the secondary combustion burners is controlled by the exhaust flue gas temperature with that temperature being held between ISO-250 F. for normal usage. As this temperature is achieved solenoid valves 48 controlled by flue gas thermostat 49 reduces the gas supplied to the burners to minimize gas consumption, but still to heat the infiowing gases to a high combustion temperature.

For burning refuse in the described 400 lb. incinerator the primary combustion chamber operates at a tempera ture between 800-1100 F. and the secondary combustion chamber at a temperature of 16002000 F. The temperature of the combustion products is cooled in cooling chamber 18 to the range of l000l500 F. with about of excess air and in the spray cooling chamber to a flue gas temperature of ISO-250 F.

Various modifications to the described apparatus may become apparent to those familiar with this art without departing from the scope of the invention. The foregoing description therefore has ben given for illustrative purposes and clearness of understanding only, and no unnecessary limitations should be understood therefrom. The invention is defined in the following claims.

I claim:

1. A compact incinerator for completely burning combustible material comprising: means defining three vertically stacked chambers, the lowermost chamber being a primary combustion chamber, the intermediate chamher being a secondary combustion chamber, and the uppermost chamber being a cooling chamber; said primary combustion chamber having an air inlet opening and communicating with said secondary combustion chamber through an orifice; said second combustion chamber having a second air inlet opening and communicating with said cooling chamber through a restricted opening; said cooling chamber having a third air inlet opening and a discharge opening; burner means disposed within said primary combustion chamber for igniting combustible material; second burner means disposed within said secondary combustion chamber for supplementing heat generated by complete burning of volatilized material passing through said chamber; and means for exhausting gases through the discharge opening of said cooling chamber while simultaneously inducing an air flow through said primary and secondary combustion chambers, said first air inlet opening admitting insufiicient air 'for complete combustion but sufficient to partially burn and volatilize combustible material, said second air inlet opening admitting a metered amount of air for complete combustion in said second chamber, and said third air inlet opening admitting a volume of air approximately equal to gases emitted through said restricted opening to materially reduce the temperature of gases withdrawn from said second combustion chamber into said cooling chamber.

2. The compact incinerator as described in claim 1 wherein said first inlet opening transmits about 65-75% of the theoretical amount of combustion air required to sustain complete burning of combustible material within said primary combustion chamber.

3. The compact incinerator described in claim 1 and further comprising bafile means disposed within said cooling chamber intermediate said third inlet opening and said discharge opening for mixing the combustion prod nets with cooling air.

4. The compact incinerator described in claim 1 and further comprising a spray chamber communicating with the discharge opening from said cooling chamber, said means for exhausting gases from said discharge opening communicating with said spray chamber; and means within said spray chamber for spraying a cooling media into intimate contact with combustion products exhausted from the cooling chamber.

References Cited by the Examiner UNITED STATES PATENTS 830,974 9/1906 Decarie 110-8 1,877,214 9/1932 Woodman. 2,625,121 1/ 1953 Vanderwerf. 2,912,941 11/1959 Hughes et al 1l08 DONLEY J. STOCKING, Primary Examiner.

JOHN J. CAMBY, Examiner.

FREDERICK L. MATTESON, JR., Assistant Examiner. 

1. A COMPACT INCINERATOR FOR COMPLETELY BURNING COMBUSTIBLE MATERIAL COMPRISING: MEANS DEFINING THREE VERTICALLY STACKED CHAMBERS, THE LOWERMOST CHAMBER BEING A PRIMARY COMBUSTION CHAMBER, THE INTERMEDIATE CHAMBER BEING A SECONDARY COMBUSTION CHAMBER, AND THE UPPERMOST CHAMBER BEING A COOLING CHAMBER; SAID PRIMARY COMBUSTION CHAMBER HAVING AN AIR INLET OPENING AND COMMUNICATING WITH SAID SECONDARY COMBUSTION CHAMBER THROUGH AN ORIFICE; SAID SECOND COMBUSTION CHAMBER HAVING A SECOND AIR INLET OPENING AND COMMUNICATING WITH SAID COOLING CHAMBER THROUGH A RESTRICTED OPENING; SAID COOLING CHAMBER HAVING A THIRD AIR INLET OPENING AND A DISCHARGE OPENING; BURNER MEANS DISPOSED WITHIN SAID PRIMARY COMBUSTION CHAMBER FOR IGNITING COMBUSTIBLE MATERIAL; SECOND BURNER MEANS DISPOSED WITHIN SAID SECONDARY COMBUSTION CHAMBER FOR SUPPLEMENTING HEAT GENERATED BY COMPLETE BURNING OF VOLATILIZED MATERIAL PASSING THROUGH SAID CHAMBER; AND MEANS FOR EXHAUSTING GASES THROUGH THE DISCHARGE OPENING OF SAID COOLING CHAMBER WHILE SIMULTANEOUSLY INCLUDING AN AIR FLOW THROUGH SAID PRIMARY AND SECONDARY COMBUSTION CHAMBERS, SAID FIRST AIR INLET OPENING ADMITTING INSUFFICIENT AIR FOR COMPLETE COMBUSTION BUT SUFFICIENT TO PARTIALLY BURN AND VOLATILIZE COMBUSTIBLE MATERIAL, SAID SECOND AIR INLET OPENING ADMITTING A METERED AMOUNT OF AIR FOR COMPLETE COMBUSTION IN SAID SECOND CHAMBER, AND SAID THIRD AIR INLET OPENING ADMITTING A VOLUME OF AIR APPROXIMATELY EQUAL TO GASES EMITTED THROUGH SAID RESTRICTED OPENING TO MATERIALLY REDUCE THE TEMPERATURE OF GASES WITHDRAWN FROM SAID SECOND COMBUSTION CHAMBER INTO SAID COOLING CHAMBER. 